by G. Bartley

When the CZU wildfire burned 86,500 acres, including the first ever recorded location of a marbled murrelet’s nest–in Big Basin Redwoods State Park–it was feared it could be a major if not final blow to the already endangered seabird’s presence in the Santa Cruz mountains. Yet just one year later, another incredible first occurred in Big Basin, a marbled murrelet was filmed fledging its nest. This was a great sign of hope for the resilience of the redwood forest, the Santa Cruz mountains, and for this struggling species in the most southern stronghold of its range.

Marbled murrelets, described as a flying potato, spend much of their life on the ocean but like the coho salmon make their way inland to the forests to lay their eggs. Nesting atop old-growth trees like the redwoods and Douglas-firs in the Santa Cruz mountains, Ornithologist Steve Singer had estimated about 50% of their suitable habitat had been lost in Big Basin Redwoods State Park. While nearly all of the redwoods are expected to recover in time, their canopies were still impacted and a much heavier toll was taken on their less fire resistant Douglas-fir neighbors which are unable to recover through epicormic sprouting as redwoods can. Needless to say, the CZU wildfire left the fate of the seabird looking bleak until a nest was discovered in Big Basin again in 2021.

Adapted to return to the forest for nesting, adult marbled murrelets turn a mottled brown during breeding season, making them more difficult to spot in the canopy. Despite being described as potatoes, they are deceptively fast. Their stubby wings–suited for flying underwater–are also well-adapted for the forest. Beatrix says they can fly up to 100 miles per hour–to help them evade predators in the forest. Their comparatively small wing size means they have to beat their wings constantly and rapidly to stay aloft.

Perhaps more potato-like, is their maneuverability. Although they have fast wing beats, they can’t hover like hummingbirds nor can they make any sudden turns. A hummingbird beats its wings between 10 and 80 times per second. Having been trained to conduct inland field surveys for marbled murrelets the last two years, Beatrix can attest to hearing their fast wing beats–which she says sound like a boomerang– and their calls–referred to as “keers”– across the sky far more often than she could track them flying under the cover of darkness.

Marbled murrelet calling bout spectogram, by Conservation Metrics

While most of our properties burned in the CZU wildfire’s considerable footprint, remarkably marbled murrelets have been detected at 3 out of 5 monitoring locations. So how do we monitor for these rare, elusive birds unlikely to be seen in-person or to conveniently land in front of a monitoring camera? Through the air. Acoustic Recording Units set to record at marbled murrelets’ most active times in the forest–around sunrise and sunset–were set at 5 different locations by staff. The hundreds of hours of field recordings were then processed with a pattern recognition software to specifically detect the “keer” calls of marbled murrelets allowing the researchers to hone their manual review in on high probability calls and check for the sound of wing beats before and after which could indicate proximity to a nesting site.

Steller's jay at San Vicente Redwoods by Pathways For Wildlife

The Audio Recording Units were able to record detections of marbled murrelets, but the recording can’t tell us if the marbled murrelets are nesting or whether any marbled murrelets hatched–although wing beats would have been an indication. For that, Beatrix says the first step would be in-person surveys to confirm if they’re occupying the tree stands. To increase the effectiveness and efficiency of in-person surveys, Beatrix will meet with other land managers and experts in the Zone 6 area–U.S. Fish and Wildlife Service’s official name for this section of marbled murrelet habitat–to coordinate collective efforts to monitor marbled murrelets with Acoustic Recording Units and in-person surveys. In the long term, potential nesting habitat at San Vicente Redwoods is being restored to enhance conditions for the forest and for marbled murrelets. For now, the marbled murrelets are out to sea.

While we await their return, we can all play an important part in helping to prepare for potential nesting by keeping our parks and lands “Crumb Clean”. Marbled murrelet eggs can fall prey to corvids including jays, ravens, and crows, which tend to follow human presence in hopes of crumbs. As the trails at San Vicente Redwoods open, we’ll continue to monitor for corvids to see if human presence leads to an increase in these opportunistic birds and identify whether any changes in use are needed to help protect marbled murrelets.

You can read about a rare marbled murrelet fledgling encounter and our regional in-depth monitoring to support this endangered species.

by USFWS

Important nocturnal pollinators and natural insect control, bats are an important part of the ecosystem and have been known to roost in the hollows of redwoods among other places–including a pond at San Vicente Redwoods where a bat detector was installed this fall. Once the acoustic sensor has been analyzed to determine which species have been detected, Dr. Winifred Frick with Bat Conservation International hopes to be able to monitor bats on the property more extensively when they are more active in the late spring and summer months. In the meantime, you can read about bats documented at San Vicente Redwoods during previous surveys.